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readfile> <pclose
[edit] Last updated: Sat, 12 May 2012

view this page in

popen

(PHP 4, PHP 5)

popenOpens process file pointer

Description

resource popen ( string $command , string $mode )

Opens a pipe to a process executed by forking the command given by command.

Parameters

command

The command

mode

The mode

Return Values

Returns a file pointer identical to that returned by fopen(), except that it is unidirectional (may only be used for reading or writing) and must be closed with pclose(). This pointer may be used with fgets(), fgetss(), and fwrite(). When the mode is 'r', the returned file pointer equals to the STDOUT of the command, when the mode is 'w', the returned file pointer equals to the STDIN of the command.

If an error occurs, returns FALSE.

Examples

Example #1 popen() example

<?php
$handle 
popen("/bin/ls""r");
?>

If the command to be executed could not be found, a valid resource is returned. This may seem odd, but makes sense; it allows you to access any error message returned by the shell:

Example #2 popen() example

<?php
error_reporting
(E_ALL);

/* Add redirection so we can get stderr. */
$handle popen('/path/to/executable 2>&1''r');
echo 
"'$handle'; " gettype($handle) . "\n";
$read fread($handle2096);
echo 
$read;
pclose($handle);
?>

Notes

Note:

If you're looking for bi-directional support (two-way), use proc_open().

Note: When safe mode is enabled, you can only execute files within the safe_mode_exec_dir. For practical reasons, it is currently not allowed to have .. components in the path to the executable.

Warning

With safe mode enabled, the command string is escaped with escapeshellcmd(). Thus, echo y | echo x becomes echo y \| echo x.

See Also

  • pclose() - Closes process file pointer
  • fopen() - Opens file or URL
  • proc_open() - Execute a command and open file pointers for input/output



readfile> <pclose
[edit] Last updated: Sat, 12 May 2012
 
add a note add a note User Contributed Notes popen
anonymous at anon dot com 08-Feb-2011 01:39
If, on windows, you need to start a batch file that needs administrator privileges, then you can make a shortcut to the batch file, click properties, check to on "run as administrator" on one of the property pages, and then double-click the shortcut once (to initialize that "run as administrator" business).

using popen("/path/to/shortcut.lnk") will then run your batch file with administrator privileges.

handy for when you want to use cli php to do some long running tasks and that php-cli needs to use sessions..
mrjake2 06-Sep-2010 04:08
If you are running in a chroot'ed environment on Debian "Squeeze", this command won't work; there is a problem with the kernel code that popen() eventually calls.

Note that pecl makes heavy use of this command, so if you are running in this environment you will need to install the pecl extension from source instead.
hacklor [AT] NOSPAM [DOT] com 19-Apr-2010 09:03
There is a simple way to start a process in the background but still find out what the process result is. I combined the information from some users below with some of my own coming up with the following:

<?php
$bat_filename
= "C:\\my_bat_file.bat";
$bat_log_filename = "C:\\my_bat_file_bat.log";
$bat_file = fopen($bat_filename, "w");
if(
$bat_file) {
   
fwrite($bat_file, "@echo off"."\n");
   
fwrite($bat_file, "echo Starting proces >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "php c:\\my_php_process.php >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "echo End proces >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "EXIT"."\n");
   
fclose($bat_file);
}
           
//
// Start the process in the background
//
$exe = "start /b ".$bat_filename;
if(
pclose(popen($exe, 'r')) ) {
    return
true;
}
return
false;
?>

In my case the file names of the .bat and .log files weren't always the same, so I needed a dynamic way to create the .bat file. The output from the php command is saved to the log file with the >> command. All prints and errors are stored there. At a later time you can open the log file and see what happened.
php at keithtyler dot net 20-Jan-2010 06:26
Note that you *have* to do a read on the handle before you can feof(), even if the command outputs nothing! So..

<?php
$f
=popen("sleep 2","r");
while (!
feof($f)) {}
pclose($f);
print
"done";
?>

will never finish.
lwalker at snet dot net 17-Sep-2009 11:56
To run a php script and not wait for it I use this on windows
$commandString = "start /b c:\\php\\php.EXE c:\\image\\cleanup.php --passaccount=$account --passcount=$count";
pclose(popen($commandString, 'r'));

Note to pass my script vars you need dashdash.
to read the var use --this is in cleanup.php

<?php
function arguments($argv) {
   
$_ARG = array();
    foreach (
$argv as $arg) {
        if (
ereg('--[a-zA-Z0-9]*=.*',$arg)) {
           
$str = split("=",$arg); $arg = '';
           
$key = ereg_replace("--",'',$str[0]);
            for (
$i = 1; $i < count($str); $i++ ) {
               
$arg .= $str[$i];
            }
                       
$_ARG[$key] = $arg;
        } elseif(
ereg('-[a-zA-Z0-9]',$arg)) {
           
$arg = ereg_replace("-",'',$arg);
           
$_ARG[$arg] = 'true';
        }
   
    }
return
$_ARG;
}
sleep(5);
$var_array= arguments($argv);
extract($var_array, EXTR_PREFIX_SAME, "wddx");//$user comes from here
//echo "hello new $user";
$account=$passaccount;
$count=$passcount;
?>
webmaster at php-idee dot de 23-Jul-2009 06:36
If you try to execute a command under Windows the PHP script normally waits until the process has been terminated. Executing long-term processes pauses a PHP script even if you don't want to wait for the end of the process.

It wasn't easy to find this beautiful example how to start a process under Windows without waiting for its termination:

<?php
$commandString
= 'start /b c:\\programToRun.exe -attachment "c:\\temp\file1.txt"';
pclose(popen($commandString, 'r'));
?>
Marbug at gmail dot com 03-Feb-2009 03:43
If you want to download files from a linux server with a filesize bigger than 2GB you can use the following:

<?php
function serveFile( $file , $as ){
   
header( 'Expires: Mon, 1 Apr 1974 05:00:00 GMT' );
   
header( 'Pragma: no-cache' );
   
header( 'Cache-Control: must-revalidate, post-check=0, pre-check=0' );
   
header( 'Content-Description: File Download' );
   
header( 'Content-Type: application/octet-stream' );
   
header( 'Content-Length: '.trim(`stat -c%s "$file"`) );
   
header( 'Content-Disposition: attachment; filename="'. $as .'"' );
   
header( 'Content-Transfer-Encoding: binary' );
   
//@readfile( $file );

   
flush();
   
$fp = popen("tail -c ".trim(`stat -c%s "$file"`)." ".$file.' 2>&1', "r");
    while(!
feof($fp))
    {
       
// send the current file part to the browser
       
print fread($fp, 1024);
       
// flush the content to the browser
       
flush();
    }
   
fclose($fp);
}
?>
rockytriton 10-Sep-2007 11:25
Note, when using this with a batch file in windows, you must put an "exit" at the end of your batch file or you will get a new cmd.exe stuck in your process list every time you execute the page.
betchern0t 13-Apr-2007 09:42
Care needs to be taken in the case of long running child processes. Say you want to run tail -f /var/log/messages or in my case burn dvds. If you have a busy wait, Apache2 can sit towards 100%cpu and steadily grow memory. In my case I crashed the server after about an hour and 90% of the dvd burned. During that time apache had consumed a gig of swap.

Offending code - don't copy:

<?php
        $ThisCommand
= sprintf("%s %s",COMMAND,$ThisFile);
       
$fp=popen($ThisCommand,"r");
        while (!
feof($fp)) {
               
set_time_limit (20);
               
$results = fgets($fp, 4096);
                if (
strlen($results) == 0) {
                  
// stop the browser timing out
                  
echo " ";
                  
flush();
                } else {
                  
$tok = strtok($results, "\n");
                   while (
$tok !== false) {
                        echo
htmlentities(sprintf("%s\n",$tok))."<br/>";
                       
flush();
                       
$tok = strtok("\n");
                   }
                }
        }
       
pclose($fp);
?>

to go from zero memory and 100% cpu  to negligible memory and negligible cpu add a sleep.

<?php
       
while (!feof($fp)) {
               
set_time_limit (20);
               
$results = fgets($fp, 256);
                if (
strlen($results) == 0) {
                  
// stop the browser timing out
                  
echo " ";
                  
flush();
                } else {
                  
$tok = strtok($results, "\n");
                   while (
$tok !== false) {
                        echo
htmlentities(sprintf("%s\n",$tok))."<br/>";
                       
flush();
                       
$tok = strtok("\n");
                   }
                }
               
// avoid a busy wait
               
sleep(1);

        }
?>

I think the continued banging of the space to keep the browser awake triggered some issues in apache.
Nate 20-Oct-2006 04:21
Note that under Windows, if you are trying to write data to be available to your pipe's STDIN, you may need to execute php directly, rather than depending on file associations.

<?php
   
// with $cmd set to 'foo.php', STDIN comes up blank.
    // with $cmd set to 'php foo.php', STDIN gets filled
    //     (assuming php.exe is in your path)
   
$cmd = 'foo.php';

    if ( (
$fh = popen($cmd, 'w')) === false )
        die(
"Open failed: ${php_errormsg}\n");

   
fwrite($fh, "Line one\nLine two\n");

   
pclose($fh);
?>
nospam at spamalot dot com 30-Aug-2006 06:19
popen() seems to have problems dealing with binary data (piping audio data to the standard input of an encoding application). I changed to proc_open() instead and now everything is working fine.
Christian 09-May-2006 11:33
Thanks a lot to tr4nc3 at msn dot com..
when using apache on Windows XP, on 'console mode' commands work fine, but as a system service, commands like 'popen' stop functioning, to resolve this:

Start>Run>services.msc
Right click "Apache...", select properties.
Click on the "LOG ON" tab
Check the box "Allow this service to interact with desktop"
Click OK
Restart Apache
don at digithink dot com 19-Dec-2005 04:28
<?php
// The above import function can be easily extended using
// /usr/local/bin/xls2csv (part of catdoc ) and popen
// to read excell files directly.
// In our particular application the first line was the file heading.
function importxls($file,$head=true,$throwfirst=true,$delim=",",$len=1000) {
  
$return = false;
  
$handle = popen("/usr/local/bin/xls2csv $file", "r");
// or die if not there.
  
if ($throwfirst) {
      
$throw = fgetcsv($handle, $len, $delim);
   }
   if (
$head) {
      
$header = fgetcsv($handle, $len, $delim);
   }
   while ((
$data = fgetcsv($handle, $len, $delim)) !== FALSE) {
       if (
$head AND isset($header)) {
           foreach (
$header as $key=>$heading) {
              
$row[$heading]=(isset($data[$key])) ? $data[$key] : '';
               print
"<li>". $heading ."=>" . $row[$heading]."</li>";
           }
          
$return[]=$row;
       } else {
          
$return[]=$data;
       }
   }
  
fclose($handle);
   return
$return;
}
?>
rjl at xs4all dot nl 23-Nov-2005 01:16
Truncated output from ps command?

The solution lies in the way ps displays it's info
specifically the -w option which:
'uses 132 columns to display information,
instead of the default which is your window size.'....
somehow with fgets in php that results in 74 characters
regardless off the init length parameter

a bit of code:

<?php
echo '<table width="99%"><tr><td>cron</td></tr>' . "\n";
$fp=popen("/bin/ps -waux","r");
while (!
feof($fp)) {
   
$buffer = fgets($fp, 4096);
   
$croninf .= '<tr><td>' . $buffer . '</td></tr>' . "\n";
}
pclose($fp);
echo
$croninf;
echo
'</table><br><br>' . "\n";
?>

Ciao,

Rene =<>=
erb at agricola-gymnasium dot de 06-Oct-2005 05:48
Writing and executing a bash script is as simple as that:

<?php
$f
= popen ("/bin/bash","w");
fwrite($f, "export KRB5CCNAME=`tempfile`\n");
fwrite($f, "export KRBTKFILE=`tempfile`\n");
fwrite($f, "$KINIT --keytab=$GLOBALS["KADMIN_KEYFILE"] --use-keytab --afslog $GLOBALS["KADMIN_PRINC"]\n");
fwrite($f, "pts delete $uid\n");
fwrite($f, "fs rmmount $rwhome\n");
fwrite($f, "vos remove sanjo b user.$uid\n");
fwrite($f, "$KDESTROY\n");
pclose($f);
?>
Cride5 08-Sep-2005 05:39
Here is a nice little script for monitoring your http access log.

<?php

$handle
= popen("tail -f /etc/httpd/logs/access.log 2>&1", 'r');
while(!
feof($handle)) {
   
$buffer = fgets($handle);
    echo
"$buffer<br/>\n";
   
ob_flush();
   
flush();
}
pclose($handle);

?>

----
www.eviltree.co.uk
www.solidsites.co.uk
www.mongbong.com
atampone at NOSPAMFORME dot trdsupra dot com 20-Jun-2005 06:26
If you want to fork a process under windows, this is the function to use.  I created a batch file called runcmd.bat with the following line

start %1 %2 %3 %4

then I have the folowing function

<?php
define
('RUNCMDPATH', 'c:\\htdocs\\nonwebspace\\runcmd.bat');

function
runCmd($cmd) {
   
$externalProcess=popen(RUNCMDPATH.' '.$cmd, 'r');
   
pclose($externalProcess);
}   
?>

with this, doing something like

<?php runCmd('php.exe printWorkOrder.php 3498'); ?>
will launch php.exe outside of apache and allow the script calling the runCmd() function to continue without waiting for the command line process to return.  The process will run under the same user account that Apache (or whatever webserver you're running) is running under, so make sure it has permissions to do whatever you need to do.  Also, make sure that the batch file has enough %n s in order to pass all the command line variables that you might need to pass.

Special thanks to kicken from the devshed forums for coming up with the idea.
PGP Dude 06-May-2005 12:30
I should say, my host uses a modified form of safe mode, so I don't know if that might have caused a problem with "popen" as opposed to "proc_open".  With safe mode enabled, all words following the initial command string are treated as a single argument. Thus, echo y | echo x becomes echo "y | echo x".  [Because of this,] LinixDude010's srcipt did not work for me.  Seems wrong to read and write with popen, according to the manual.

The script produced pgp text, but there was something wrong with the text and I could not decode it.

This replacement script, using proc_open, which can read and write, DOES work:

<?php
function pgp_encrypt($keyring_location, $public_key_id, $plain_text) {
 
$encrypted_text='';
 
$key_id = EscapeShellArg($public_key_id);
 
putenv("PGPPATH=$keyring_location");

 
// encrypt the message
 
$descriptorspec = array(
   
0 => array("pipe", "r"),  // stdin
   
1 => array("pipe", "w"),  // stdout
   
2 => array("pipe", "w")   // stderr ?? instead of a file
 
);
 
$process = proc_open("pgpe -r $key_id -af", $descriptorspec, $pipes);
  if (
is_resource($process)) {
   
fwrite($pipes[0], $plain_text);
   
fclose($pipes[0]);
    while(
$s= fgets($pipes[1], 1024)) {
         
// read from the pipe
         
$encrypted_text .= $s;
    }
   
fclose($pipes[1]);
   
// optional:
   
while($s= fgets($pipes[2], 1024)) {
     
$encrypted_text.= "\n<p>Error: $s</p>\n";
    }
   
fclose($pipes[2]);
  }
  return
$encrypted_text;
}

$message = pgp_encrypt("/home/username/.pgp", "to@domain.com", "dummy text to be encrypted");
print
nl2br($message);

?>
shaun at nospam dot phplabs dot com 27-Feb-2005 05:52
Note that there appears to be a limit to the amount of data that fread() will return from a handle opened with popen(). A call to fread() may not return as much as you ask for.

For example, suppose I have a file "myfile.txt" which is more than 10KB in size. The following code works as expected:

<?php
$fp
= fopen('myfile.txt', 'r');
$data = fread($fp, 10240);
echo
strlen($data);
?>

The output is '10240.' However, popen() behaves differently:

<?php
$fp
= popen('/bin/cat myfile.txt', 'r');
$data = fread($fp, 10240);
echo
strlen($data);
?>

On my system, this code prints out '8192' instead of the expected '10240.'
kalvinb602 at hotmail dot com 06-Jul-2004 03:42
If you're having trouble with the server (Apache) hanging when issuing system commands consider the following bug report:

http://bugs.php.net/bug.php?id=22526

basically, if you're using sessions issue a

session_write_close();

command before you execute your system command to keep the server from hanging.

This may also correct the problem when using other system command executing functions like exec.

Ben
Michel Machado 06-Mar-2004 05:53
Yet another workaround for not having bidirectional pipes in php.

<?php
$Cmd
=
"bc 2>&1 << END\n" .
"100+221\n" .
"1+3*3\n" .
"quit\n" .
"END\n";

$fp = popen($Cmd, 'r');
$read = fread($fp, 1024);
echo
$read;
pclose($fp);
?>
http://vmlinuz.nl/about/contact/ 11-Nov-2002 08:58
From the popen linux programmers manual:

"The  command  argument  is  a pointer to a null-terminated string containing a shell command line.  This  command  is passed  to  /bin/sh  using the -c flag."

Since php uses this popen function, you need to be sure /bin/sh exists. This file may not exist in chroot()ed environments.
ajv-php at erkle dot org 08-Aug-2002 11:02
I noticed that some of the examples above seem to advocate passing unencrypted data to gpg via the pipe shell escape, in the absence of a bi-directional popen (on some OSes).

The approach I've taken is similar to:

<?php
  $prefix
= 'example';
 
$command = '/usr/local/bin/gpg --encrypt --armor --no-tty --batch --no-secmem-warning --recipient "joe.soap@example.com"';
 
$tmpfile = tempnam('/tmp', $prefix);
 
$pipe = popen("$command 2>&1 >$tmpfile", 'w');
  if (!
$pipe) {
   
unlink($tmpfile);
  } else {
   
fwrite($pipe, $plaintxt, strlen($plaintxt));
   
pclose($pipe);
   
$fd = fopen($tmpfile, "rb");
   
$output = fread($fd, filesize($tmpfile));
   
fclose($fd);
   
unlink($tmpfile);
  }
  return
$output;
?>

This means that unencrypted information is not passed via a (potentially readable) shell command, and only encrypted information gets stored on disc.
12-Jul-2002 02:33
Here is a workaround for not having bidirectional pipes in php.

If you have bidirectional pipe support, don't bother with this.

The trick here is to send the input on the command line to the target application.  In particular I wanted to use openssl without using temp files or named pipes.  This solution should also be thread/process safe.

This does work on Linux (RedHat 7).

<?php
function filterThroughCmd($input, $commandLine) {
 
$pipe = popen("echo \"$input\"|$commandLine" , 'r');
  if (!
$pipe) {
    print
"pipe failed.";
    return
"";
  }
 
$output = '';
  while(!
feof($pipe)) {
   
$output .= fread($pipe, 1024);
  }
 
pclose($pipe);
  return
$output;
}

# example:
print filterThroughCmd("hello", "cat");
# Piping to cat has the effect of echoing your input.
?>
cyberlot at cyberlot dot net 30-Jun-2002 01:29
The below code works for both way processing ;) Have fun folks

<?php
    system
("mkfifo pipeout");
  
$pipe = popen("./nwserver -module Chapter1E > pipeout","w");
  
$pipeout = fopen("pipeout", "r");
   while (
$s = fgets($pipeout,1024)) {
    echo
$s;
   }

?>
linuxdude010 at yahoo dot com 24-May-2002 11:49
I had all kinds of trouble encrypting a message with PGP, but I finanlly got it to work.  The trick was to 'chmod o+r pubring.pkr' so that the apache server could read the public keys!!!  Then, this function worked fine:

<?PHP
function pgp_encrypt($keyring_location, $public_key_id, $plain_text) {

       
$key_id = EscapeShellArg($public_key_id);
       
putenv("PGPPATH=$keyring_location");

       
// encrypt the message
       
$pipe = popen("pgpe -r $key_id -af", "r");              
       
fwrite($pipe, $plain_text);
       
$encrypted_text = '';
        while(
$s = fgets($pipe, 1024)) {
               
// read from the pipe
               
$encrypted_text .= $s;
        }
       
pclose($pipe);

        return
$encrypted_text;
}

$message = pgp_encrypt("/home/username/.pgp", "to@domain.com", "dummy text to be encrypted");
print
nl2br($message);

?>
nricciardi at mindspring dot com 08-Mar-2002 04:38
ive tried using popen using bidirectional pipes without working for obvious reasons, but i managed to create a simple script that managed to take care of the problem.  This example is for gpg encryption.

<?php
   $message
= "this is the text to encrypt with gpg";
  
$sendto = 'Dummy Key <another@fake.email>';

  
system("mkfifo pipein");
  
system("mkfifo pipeout");
  
system("gpg --encrypt -a -r '$sendto' > pipeout < pipein &");
  
$fo = fopen("pipeout", "r");
  
$fi = fopen("pipein", "w");
  
fwrite($fi, $message, strlen($message));
  
fclose($fi);
   while (!
feof($fo)) {
     
$buf .= fread($fo, 1024);
   }
   echo
$buf;
  
unlink("pipein");
  
unlink("pipeout");
?>

If anyone has a better way of doing this I would love to see it.
kevin at pricetrak dot com 29-Jun-2001 11:26
Just a quick note about your environment. None of the apache specific environment variables are available to the called program.
trevor at verite dot com 16-Feb-2001 12:42
Just make sure that you check the user information being passed into the command (if any) before it executes.
matthew at leftcoast dot com 04-Oct-2000 06:16
Note that your OS must support bi-direction pipes for popen to be bi-directional. 

FreeBSD and BSDI are known to support bi-pipes. 

Not sure about Linux.

 
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